/****************************************************************************
 *  ggentry.c
 *
 *  Genesis Plus GX Game Genie 
 *
 *  Softdev (2006)
 *  Eke-Eke (2007,2008,2009)
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 ***************************************************************************/

#include "shared.h"
#include "font.h"
#include "gui.h"

#define MAXCODES 8

typedef struct
{
  int address;
  unsigned short data;
} GGPATCH;

/*** Game Genie Codes Array ***/
unsigned char ggcodes[MAXCODES][10];  /*** Codes are entered as XXXX-XXXX ***/
int gghpos[MAXCODES];    /*** Edit positions ***/
int ggrow = 0;
int editing = 0;
char ggvalidchars[] = "ABCDEFGHJKLMNPRSTVWXYZ0123456789*";
GGPATCH ggpatch[8];

/****************************************************************************
 * Decode Game Genie entries to memory patches
 ****************************************************************************/
void decode_genie (char *code, int which)
{
  char *p;
  int n, i;
  for (i = 0; i < 8; i++)
  {
    /*** This should only happen if memory is corrupt! ***/
    p = strchr (ggvalidchars, code[i]);
    if (p == NULL)
    {
      ggpatch[which].address = ggpatch[which].data = 0;
      return;
    }

    n = p - ggvalidchars;

    switch (i)
    {
      case 0:
      ggpatch[which].data |= n << 3;
      break;

      case 1:
      ggpatch[which].data |= n >> 2;
      ggpatch[which].address |= (n & 3) << 14;
      break;

      case 2:
      ggpatch[which].address |= n << 9;
      break;

      case 3:
      ggpatch[which].address |= (n & 0xF) << 20 | (n >> 4) << 8;
      break;

      case 4:
      ggpatch[which].data |= (n & 1) << 12;
      ggpatch[which].address |= (n >> 1) << 16;
      break;

      case 5:
      ggpatch[which].data |= (n & 1) << 15 | (n >> 1) << 8;
      break;

      case 6:
      ggpatch[which].data |= (n >> 3) << 13;
      ggpatch[which].address |= (n & 7) << 5;
      break;

      case 7:
      ggpatch[which].address |= n;
      break;
    }
  }
}

void decode_ggcodes ()
{
  int i, j;
  char thiscode[10];

  /*** Clear out any old patches ***/
  memset (&ggpatch[0], 0, 8 * sizeof (GGPATCH));
  memset (&thiscode, 0, 10);

  j = 0;
  for (i = 0; i < 8; i++)
  {
    if (strcmp ((char *)ggcodes[i], "AAAA-AAAA"))
    {
      /*** Move the code into thiscode ***/
      memcpy (&thiscode, &ggcodes[i], 4);
      memcpy (&thiscode[4], &ggcodes[i][5], 4);

      decode_genie (thiscode, j);
      j++;
    }
  }

  /*** And now apply the patches ***/
  if (j)
  {
    for (i = 0; i < j; i++)
    {
      if (ggpatch[i].address < 0x400000)
      {
        /*** Patching ROM space ONLY (Game Genie does NOT have access to other memory areas) ***/
        if (cart.rom) *(uint16 *)(cart.rom + ggpatch[i].address) = ggpatch[i].data & 0xffff;
      }
    }
  }
}

/****************************************************************************
 * ClearGGCodes
 *
 * Should be called whenever a new rom is loaded
 ****************************************************************************/
void ClearGGCodes ()
{
  int i;

  for (i = 0; i < MAXCODES; i++)
  {
    strcpy ((char *)ggcodes[i], "AAAA-AAAA");
    gghpos[i] = 0;
  }
  ggrow = 0;
}

/****************************************************************************
 * DrawGGCodes
 *
 * Just draw the codes, with the current one highlighted.
 ****************************************************************************/
void DrawGGCodes ()
{
  int i,j;
  unsigned char c[2] = { 0, 0 };

  gxClearScreen ((GXColor)BLACK);
  WriteCentre (134, "Game Genie Entry");

  for (i = 0; i < MAXCODES; i++)
  {
    if (i == ggrow)
    {
      /*** Highlight selected ***/
      WriteCentre_HL (i * fheight + 190, (char *)ggcodes[i]);

      /*** If editing, highlight the current character ***/
      if (editing)
      {
        int hpos = 0;

        for (j=0; j<strlen ((char *)ggcodes[i]); j++) hpos += font_size[ggcodes[i][j]];
        hpos = ((640 - hpos) >> 1);
        for (j=0; j<gghpos[i]; j++) hpos += font_size[ggcodes[i][j]];

        c[0] = ggcodes[i][gghpos[i]];
        fntDrawBoxFilled (hpos, (i * fheight) + 190, hpos + font_size[c[0]],
                          ((i + 1) * fheight) + 190, COLOR_YELLOW);
        write_font (hpos, (i * fheight) + 190, (char *)c);
      }
    }
    else WriteCentre ((i * fheight) + 190, (char *)ggcodes[i]);
  }
  gxSetScreen();
}

/****************************************************************************
 * GGEditLine
 *
 * Up/Down traverses valid character array
 * Left/Right moves along current line
 * A exits edit mode
 ****************************************************************************/
void GGEditLine ()
{
  short p;
  char c[2] = { 0, 0 };
  char *v;
  int redraw = 1;
  int quit = 0;

  editing = 1;

  while (quit == 0)
  {
    if (redraw)
    {
      DrawGGCodes ();
      redraw = 0;
    }

    p = m_input.keys;

    if (p & PAD_BUTTON_UP)
    {
      /*** Increment the entry ***/
      redraw = 1;
      c[0] = ggcodes[ggrow][gghpos[ggrow]];
      v = strstr (ggvalidchars, c);
      v++;
      if (*v == '*') ggcodes[ggrow][gghpos[ggrow]] = 'A';
      else ggcodes[ggrow][gghpos[ggrow]] = *v;
    }

    if (p & PAD_BUTTON_DOWN)
    {
      /*** Decrement entry ***/
      redraw = 1;
      c[0] = ggcodes[ggrow][gghpos[ggrow]];
      v = strstr (ggvalidchars, c);
      if (*v == 'A') ggcodes[ggrow][gghpos[ggrow]] = '9';
      else
      {
        v--;
        ggcodes[ggrow][gghpos[ggrow]] = *v;
      }
    }

    if (p & PAD_BUTTON_LEFT)
    {
      redraw = 1;
      gghpos[ggrow]--;
      if (gghpos[ggrow] == 4) gghpos[ggrow]--;
    }

    if (p & PAD_BUTTON_RIGHT)
    {
      redraw = 1;
      gghpos[ggrow]++;
      if (gghpos[ggrow] == 4) gghpos[ggrow]++;
    }

    if (gghpos[ggrow] < 0) gghpos[ggrow] = 8;
    if (gghpos[ggrow] > 8) gghpos[ggrow] = 0;

    if (p & PAD_BUTTON_A) quit = 1;
  }

  editing = 0;
}

/****************************************************************************
 * GGSelectLine
 *
 * Select which line to edit
 ****************************************************************************/
void GGSelectLine ()
{
  int redraw = 1;
  int quit = 0;
  short j;

  /*** To select a line, just move up or down.
    Pressing A will enter edit mode.
    Pressing B will exit to caller.   ***/

  while (quit == 0)
  {
    if (redraw)
    {
      DrawGGCodes ();
      redraw = 0;
    }

    j = m_input.keys;

    if (j & PAD_BUTTON_UP)
    {
      ggrow--;
      redraw = 1;
    }

    if (j & PAD_BUTTON_DOWN)
    {
      ggrow++;
      redraw = 1;
    }

    if (ggrow < 0) ggrow = MAXCODES - 1;
    if (ggrow == MAXCODES) ggrow = 0;

    if (j & PAD_BUTTON_B) quit = 1;

    if (j & PAD_BUTTON_A)
    {
      GGEditLine ();
      redraw = 1;
    }

    if (j & PAD_TRIGGER_Z)
    {
      /* reset code */
      strcpy ((char *)ggcodes[ggrow], "AAAA-AAAA");
      gghpos[ggrow] = 0;
      redraw = 1;
    }
  }
}

/****************************************************************************
 * GetGGEntries
 *
 * Screen to return encoded Game Genie codes.
 * No keyboard is available, so it's just a simple wrap round each line kind
 * of thing. 
 ****************************************************************************/
void GetGGEntries ()
{
  editing = 0;
  GGSelectLine ();

  /* Apply Game Genie patches */
  decode_ggcodes (); 
}